May Gardening

Whether you’re looking for ways to help mom out in her garden on Mother’s Day, or just hoping to set your own garden up for summer survival, this month is sure to keep you busy outdoors! There are plenty of blooming beauties we can still plant before the heat of summer comes on, our fruits and veggies are ripening, and we’re stepping up watering frequency to keep many of our garden plants happy. Here is Civano Nursery’s gardening list for May!

A complete veggie garden guide and calendar of planting dates published by the University of Arizona can be viewed here (Tucson’s elevation is between 2,000 and 3,000 feet)

What NOT to Plant in May

Summer-dormant succulents

Plants that are sensitive to high heat

cool-season veggies and herbs

What to Fertilize

Potted annuals: every 2 weeks with a water-soluble fertilizer at the strength recommended for houseplants

too much nitrogen can cause some plants to put on more green growth at the expense of blooms, so if you’re getting good green growth but not many flowers you may need to switch to a fertilizer with less nitrogen.

Containerized succulents: every 2 weeks with a water-soluble fertilizer at half the strength recommended for houseplants

Feed citrus trees around Memorial Day – This should be the second citrus feeding for the year (the first is around Valentine’s Day, and the third is around Labor Day).

This PDF by the University of Arizona has detailed directions for figuring out how much food to give each of your trees, regardless of what fertilizer you use.

Make sure to give your tree a good, deep drink before and after feeding

Bermuda and St. Augustine lawns

Summer-growing perennials: with a balanced, slow-release fertilizer

Water the plants deeply before and after fertilizing

Containerized roses: monthly with a water soluble fertilizer, or once every 2 months with a granular slow release fertilizer through the summer

This is the month to cut back on fertilizing roses that are in the ground. Reduce frequency of fertilizing to every 6 weeks, switch to slow-release granular fertilizer if you spring-feed with a water-soluble plant food, or completely stop fertilizing until fall.

Organic fertilizers can be used through the summer, and regular fertilizers can be used at half-strength if necessary

Established palm trees: with a balanced fertilizer, or one formulated specifically for palms

Native trees: every other month through the summer, and other trees once a month

Non-native trees: once a month through the summer

Summer-growing herbs like basil, mint and Mexican oregano can be fertilized this month with a low nitrogen organic formula

Cut back spent flowering stalks from spring-flowering perennials (unless you want to save the seed). This will either keep them blooming or help them conserve the energy that they would have put into seed production

Remove flowering stems from bulbs or iris before seeds begin to form (unless you’re planning to save the seed)

Don’t cut back the leaves of iris or bulbs – wait for the leaves to completely dry up before removing them

divide aloes that have become too overcrowded

Cut back cacti to control size or remove damaged or diseased stems

make cuts with a sharp tool at a joint if possible, or cut back to as close to the base as possible for multi-stemmed, columnar cactus

treat cuts with dusting sulphur

Remove any suckers that begin to grow from below the graft on your fruit trees as soon as you notice them

Mow established lawns regularly, removing only the top 1/3 of the blades each time you mow

Deadhead roses and remove any new flower buds before they open, but it’s best to hold off on heavy pruning until temperatures begin to cool down in fall

Fall-flowering shrubs and carefully-shaped hedges or landscape shrubs can be lightly pruned to re-shape this month

Palo verdes and mesquites can be pruned lightly this month to remove dead limbs and smaller branches, but save heavy pruning for later in the summer, when pruning is less likely to spur lots of branch re-growth

Cut back basil and mint regularly to keep them from flowering at the expense of foliar growth

For the Fruits and Veggies

Plant citrus trees

newly planted citrus trees should be watered every 5 -7 days through the first summer

Feed citrus trees around Memorial Day – This should be the second citrus feeding for the year (the first is around Valentine’s Day, and the third is around Labor Day).

Several fig varieties are ripening this month. Use bird netting around the canopy to protect fruit from birds, and don’t pick the fruit too early…it will only ripen while it’s on the tree!

Water deciduous fruit trees every 3-5 days to a depth of 3 feet through the summer

Thin overcrowded fruit from deciduous fruit trees

Remove any suckers that begin to grow from below the graft on your fruit trees as soon as you notice them

Orange Dog Caterpillars might be showing up on your citrus tree, but they can be hard to see because they look just like bird poop! A few caterpillars won’t harm a large, established tree, but you may want to remove them from smaller, newly planted trees, or treat them with Bt (an organic product that kills caterpillars).

Begin preparation for a monsoon veggie garden this month to have it ready in time for monsoons

To help prevent corn borers, apply a drop of mineral oil to the tip of each ear of corn just as the tassels begin to turn brown

Watch for squash vine borers in your veggie garden. Sudden death of leaves or a section of the vine are common symptoms of this pest. Cut out the affected portion of the plant and destroy it.

Cut back basil and mint regularly to keep them from flowering at the expense of foliar growth

Sidedress okra with a balanced slow-release fertilizer or add compost

Water herbs every 3-5 days to a depth of 1 foot

Water veggies daily to a depth of 1 foot

Summer-growing herbs like basil, mint and Mexican oregano can be fertilized this month with a low nitrogen organic formula

For the Lawn

This is the best month to start taking steps to remove unwanted bermuda grass lawns

Water cool-season grasses every 3 days to a depth of 8-10 inches if they’re still growing

Actively-growing, warm-season grasses need water every 4 days to a depth of 8-10 inches

Fertilize bermuda and St. Augustine lawns

Dethatch overseeded bermuda lawns early in the month to give the bermuda room to grow

Bermuda lawns that are not overseededm, and most other types of turfgrass, need dethatching every 2-3 years

Mow established lawns regularly, removing only the top 1/3 of the blades each time you mow

Water Wisely

Annuals: to a depth of 1 foot, often enough to maintain moisture at that level, as often as every 2-3 days in very hot or windy weather

Bulbs: reduce watering and withhold fertilizer as the leaves begin to yellow and the plant goes dormant for the summer

Iris: when they are done blooming, reduce watering to every 10 days

watering tip: iris prefer not to be watered from overhead

Large cactus, ocotillos, and large yuccas: once this month

Agave, smaller cactus, small yuccas and most prickly pear or cholla: every 3 weeks

Barrel cactus and beavertail prickly pear: every 6 weeks

Winter succulents: as they begin to yellow, decrease watering frequency by half, and stop watering completely when they shed their leaves and go dormant

Deciduous fruit trees: every 3-5 days through the summer

Established citrus trees: every 7-10 days through the summer

newly planted citrus trees should be watered every 5 -7 days through the first summer

Strawberries: daily

Grapes: every 5 days through the summer

Cool-season grasses: every 3 days if they’re still growing

Actively growing warm-season grasses: every 4 days to a depth of 8-10 inches

Non-native perennials: every 5-7 days to a depth of 2 feet

Containerized roses: when the top inch of the soil is dry, which may be daily when weather is hot and dry

Roses in the landscape: every 3-7 days , when a soil probe can only be pushed 6 inches into the ground

Desert or native adapted shrubs: every 3-4 weeks through the summer

Non-desert-adapted and non-native shrubs: every 2-3 weeks to a depth of 2 feet

Non-native trees: frequently enough to maintain moisture at a depth of 3 feet

Herbs: every 3-5 days to a depth of 1 foot

Veggies: daily to a depth of 1 foot

Adjust your irrigation timers if necessary to make sure plants are getting enough water. Typically, the duration of time that the water stays on (the amount of water delivered) is not changed, but the number of days between water applications will decrease as the weather continues to warm

Make sure that water is able to drain away from roots as we step up our watering regimen. Plants that sit in water for too long can develop root rot that can look a lot like drought damage on the above-ground portions of the plant

General Chores

Treat irises with a systemic insecticide for iris borers if they are a known pest in your garden

If you’re mulching, be sure that none of the mulch builds up against tree trunks or the bases of woody shrubs

Watch for grape leaf skeletonizer caterpillars on your grapes and treat early by hand-picking the caterpillars, pruning out affected portions of the plant, or treating the plant with Bt (an organic product that kills caterpillars)

Orange Dog Caterpillars might be showing up on your citrus tree, but they can be hard to see because they look just like bird poop! A few caterpillars won’t harm a large, established tree, but you may want to remove them from smaller, newly planted trees, or treat them with Bt (an organic product that kills caterpillars).

Geraniums tend to go dormant for the summer. Cut back on watering when the leaves begin to yellow and drop off of the plant, and only water enough to keep the branch tips from wilting through the summer. Provide the plant with some afternoon shade, or move it into full shade if it’s in a container. Cut back dead or damaged stems when the weather begins to cool again in fall, and resume watering regularly when new leaves begin to appear. Fertilize lightly when the plant is fully leafed out and actively growing in fall.

Make sure that water is able to drain away from plant roots as we step up our watering regimen for the summer. Plants that sit in water for too long often develop root rot that can look a lot like drought damage on the above-ground portions of the plant

Relocate potted roses to a spot that gets afternoon shade for the hottest months of summer

Give roses and evergreen shrubs morning showers to help remove dust that attracts spider mites, and to help keep powdery mildew at bay

Do you have a tree that is staked? It’s time to check that your tree stakes are still doing their job and that the tree isn’t being damaged by the staking wires. One year of staking is sufficient for most trees to get established; consider removing stakes that have been attached to the tree for longer than a year.